Marijuana is the most commonly used and abused illicit drug in the U.S. The prevalence of marijuana use (MU) increases across adolescence, peaks in the early 20s, and gradually declines thereafter. However, there is considerable individual variability in developmental trajectories of MU, with some adolescents continuing to use marijuana into early adulthood and others desisting from MU over time. While several studies have examined factors that predict MU during adolescence, little is known about the processes that promote or hinder desistance from MU into adulthood. Additionally, few studies have characterized the adverse adult outcomes associated with divergent trajectories of MU, including potential impairments in brain structure and function that may result from frequent use in adolescence. Moreover, most studies on teen MU have focused on predominately White samples, making it unclear whether the findings can be extrapolated to Black teens. This proposal will address these limitations by leveraging data from the Pittsburgh Youth Study (PYS), a prospective longitudinal study that includes 1009 boys in two cohorts followed from childhood (age 6) or early adolescence (age 12) into young adulthood (age 28 or 35). The aims are to: 1) Characterize the developmental course of MU from adolescence to adulthood and examine the risk/protective factors and early adult positive life events that influence MU in Black and White males; 2) Document the link between different developmental trajectories of MU and adult psychosocial adjustment in Black and White males; and 3) Examine the association between frequent adolescent MU and abnormalities in brain structure and function in adulthood. State-of-the-art analysis will identify varying trajectories of MU from early adolescence to adulthood. Path analysis will assess the processes by which early antisocial risk and pro social protective factors influence trajectories of MU, and determine whether positive adult life events influence deviations from ongoing MU trajectories. The adverse adult psychosocial outcomes associated with developmental patterns of MU will also be delineated. Across these analyses, we will explore potential differences in the patterns, precursors, and outcomes associated with MU in Black males relative to Whites, including examining what factors may help explain racial differences in MU. Finally, using a subsample of PYS youth who participated in a neuroimaging study (N=171), we will determine whether frequent adolescent MU is associated with gray and white matter brain abnormalities in adulthood, and brain function deficits while processing emotional cues and receiving rewards. The pioneering papers generated from this project will help to identify developmentally salient and culturally appropriate risk/protective factors that should be targeted by programs designed to prevent chronic MU. They will also elucidate the potential negative psychosocial and neurobiological consequences associated with different trajectories of MU, which can be incorporated into motivational enhancement interventions for marijuana using teens and inform public policies regarding the legalization of marijuana for medical use.